Answer
$v=0.285m/s$
Work Step by Step
We can determine the required speed as follows:
$P=\frac{U_{1\rightarrow 2}}{t}$
$\implies P=\frac{(80)(9.81)(4)}{t}=100$
This simplifies to:
$t=31.4s$
Now $v=\frac{S}{t}$
We plug in the known values to obtain:
$v=\frac{\sqrt{(32\times 0.25)^2+(4)^2}}{31.4}$
This simlifies to:
$v=0.285m/s$
